1. Field of the Invention
The present invention relates to a method of controlling a recording apparatus which comprises a thermal recording head.
2. Description of the Related Art
In a conventional recording apparatus of the type which is built in a facsimile machine or the like, a positioning member having a slit is attached to a thermal recording head and a platen roller is fitted to the slit of the positioning member, thereby establishing positioning of the thermal recording head with respect to the platen roller. When data is recorded on a recording paper, the paper is fed to a cutting position where it is cut off. Then, the recording paper is returned such that the tip end thereof is positioned to a wait position.
When the platen roller is fitted in the slit of the positioning member, there is a slight gap based on a so-called fitting tolerance between the inner side wall of the slit and the bearing of the platen roller. Accordingly, when the platen roller is fitted in the slit, the thermal recording head has a looseness or play corresponding to the fitting tolerance in the paper feed direction. In other words, the thermal recording head is movable within the range corresponding to the fitting tolerance.
In the case where the recording paper is fed in the downstream direction for recording, if the thermal recording head is momentarily moved down to the downstream end of the aforementioned movable range, that is, if the shifting of the head is completed before the start of the recording operation of the head, the shift of the head will not adversely affect the recording quality.
However, the recording head will not always shift momentarily due to a friction between the top surface of the recording head and a depression spring provided in contact with the top surface of the head or due to a friction acting on a supporting member of the recording head.
For this reason, in the conventional method, the shifting of the recording head within the allowable range in the slit might occur after the start of the recording, which results in the following disadvantages.
That is, when the recording head is shifted downstream during the recording operation to the recording paper, the recording head is positioned on a part of the recording paper on which data has already been recorded.
In this case, when the above-mentioned part of the paper is recorded with an intermediate tone between black and white, a black line as a noise appears on that part of the paper along a main scanning direction of the head due to the double printing, which results in deterioration of the recording quality.